Shutdown process can't finish : what to do ?

Thanks for all your answers :)

spiderman wrote:
Try this command: rn_shutdown now

mmmh ...
root@ReadyNas:~# rn_shutdown now
!!!!!! Use 'reboot' command to reboot. !!!!!!

And a reboot -p give :

root@ReadyNas:~# reboot -p
Broadcast message from root@ReadyNas on pts/0 (Fri, 05 Dec 2014 01:04:46 +0100):
The system is going down for reboot NOW!

I'm still waiting :|

vandermerwe wrote:
You can force a shutdown by pushing the power button for 5 seconds.

Ok, same than unplug the ac adapter ;) I just would like to avoid to brick my Nas :p

mdgm wrote:
Sounds like a service or app must be preventing it from shutting down somehow. What services are you running and what apps,do you have installed?

root@ReadyNas:~# service --status-all
 [ - ]  acpid

The acpid show up after 15 mins... I'm still waiting the command to complete...
Apps are : plex, some monitoring apps (htop, phpsys info), readynas photo2.
...
A top give me this...

top - 06:15:14 up 14 days, 13:06,  2 users,  load average: 9.46, 9.21, 9.14
Tasks: 220 total,   1 running, 172 sleeping,   0 stopped,  47 zombie
%Cpu(s):  0.3 us,  0.3 sy,  0.0 ni, 99.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   1008616 total,   979224 used,    29392 free,       20 buffers
KiB Swap:   523708 total,   294168 used,   229540 free,   283784 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
10111 root      20   0 28484 1680 1172 R   1.0  0.2   0:00.27 top
  574 root      20   0     0    0    0 S   0.3  0.0  29:51.73 fsnotify_mark
    1 root      20   0 45548 1556  376 D   0.0  0.2   0:41.02 systemd
    2 root      20   0     0    0    0 S   0.0  0.0   0:01.35 kthreadd
    3 root      20   0     0    0    0 S   0.0  0.0   0:52.05 ksoftirqd/0
    6 root      rt   0     0    0    0 S   0.0  0.0   0:01.41 migration/0
    7 root      rt   0     0    0    0 S   0.0  0.0   0:02.86 watchdog/0
    8 root      rt   0     0    0    0 S   0.0  0.0   0:01.34 migration/1
   10 root      20   0     0    0    0 S   0.0  0.0   0:46.22 ksoftirqd/1
   12 root      rt   0     0    0    0 S   0.0  0.0   0:02.41 watchdog/1
   13 root       0 -20     0    0    0 S   0.0  0.0   0:00.00 khelper
  261 root      20   0     0    0    0 S   0.0  0.0   0:02.54 sync_supers
  263 root      20   0     0    0    0 S   0.0  0.0   0:00.05 bdi-default
  265 root       0 -20     0    0    0 S   0.0  0.0   0:00.00 kblockd
  371 root      20   0     0    0    0 S   0.0  0.0   0:00.00 khubd
  378 root      20   0     0    0    0 S   0.0  0.0   0:01.65 kworker/0:0
  380 root       0 -20     0    0    0 S   0.0  0.0   0:00.00 md

2 user (2 ssh), no load at all...

Neverless, i've followed vandermerwe proposition...
Thanks again for all your replies..